1. Technical Field
The present invention relates to a projector.
2. Related Art
In a technical field of projectors, there is a widely known projector including an illuminator that outputs light, a lens integrator system that makes the light from the illuminator uniform, a light modulator that modulates the light from the lens integrator system in accordance with image information, and a projection system that projects the light from the light modulator (see JP-A-10-115803, for example). According to a projector of this type, the uniform light from the lens integrator system can be incident on an image formation region of the light modulator.
In the technical field of projectors, design that allows the following situation has been studied: a projector is installed in parallel to the ground and a projection image is projected in a position that does not directly face the front side of the projector (upward position when projector is placed on horizontal surface, downward position when projector is hung from ceiling). As a projector designed to allow the situation described above, there is a known projector of related art in which the projection system is so disposed that the optical axis of light incident on the projection system is shifted from the optical axis of the projection system in a predetermined direction (downward when projector is placed on horizontal surface, upward when projector is hung from ceiling) when the projection system is viewed in the direction in which light travels toward the projection system (see FIG. 2, which will be described later). The configuration described above allows a projection image to be projected on the side opposite the predetermined direction even with the projector installed in parallel to the ground.
The projector of the related art is, however, problematic in that the difference between the manner in which light passes through a central portion of the projection system (portion in the vicinity of optical axis) and the manner in which light passes through the periphery of the projection system produces a dim portion on the side opposite the predetermined direction (upper side when projector is placed on horizontal surface, lower side when projector is hung from ceiling) when a projection image is projected and hence causes non-uniform brightness of the projected image. The problem worsens in the case of a so-called proximity projection projector, which is a projector that projects a projection image on a nearby projection object and hence the optical axis of the light incident on the projection system is greatly shifted from the optical axis of the projection system. As a simple method for solving the problem described above, it is conceivable, for example, to adjust the brightness in the image formation region of the light modulator on a small-area basis. Using the method described above, however, reduces the amount of light incident on the bright portion of the image formation region to the brightness of the dim portion thereof, disadvantageously resulting in a difficulty in increasing light usage efficiency.